The retroreflection phenomenon takes place in all optical and optoelectronical devices and systems that use optical detectors, mirrors, CCD cameras, filters, or glasses in the focal point and in the optical measurement instruments, in general, provided that some of their optical components are retroreflective to light even for small apertures. The article studies a precise method to measure the retroreflection index of optical, opto-electronical systems, and treats the optical retroreflections which are used in applied research of light with various lasers such as: Nd:YAG first and second harmonics, He-Ne, and laser diodes. We have studies the conformity of our results to the theory of retroreflectors. We found that the retroreflection coefficient depends on laser wavelength. The article points out that at 532nm laser wavelength the retroreflection is greater than at 1064nm laser wavelength. The results of this paper can be used in applied research, and led to description of a mathematical relationship between the retroreflection index and laser wavelength.